Technical Field
The present disclosure relates to a light-emitting device and manufacturing method thereof, and in particular to a light-emitting device having a wavelength converting layer and a light-adjusting layer.
Description of the Related Art
For the solid-state light emitting elements, light-emitting diodes (LEDs) have the characteristics of low power consumption, low heat generation, long operational life, shockproof, small volume, quick response. Therefore, light-emitting diodes have been adopted widely in demands for light emitting elements within various fields, for instance, vehicles, home appliances, and lighting lamps.
There are several approaches to convert monochromatic light emitted from LEDs to other color light. For example, one approach is to dispose a wavelength conversion layer, such as a phosphor layer, on LEDs. Phosphor is a photoluminescence material, which is also known as a wavelength conversion material. Phosphor can absorb first light emitted from LEDs and generate a second light different from the first light. If the first light is not fully absorbed by the phosphor, the remaining first light can mix with the second light to generate mixing color of light.
For different view angles, if ratios of the first light emitted from LEDs and the converted second light are different, a distribution of the color or the color temperature in the mixing light is not uniform.
Furthermore, in the approach of forming the wavelength conversion layer on LEDs, a plurality of LEDs can be covered by one wavelength conversion sheet first, and then the wavelength conversion sheet is divided to form multiple wavelength conversion layers. During the dividing step, errors might happen and cause uneven thicknesses in individual wavelength conversion layer that can lead to the uneven distribution of the color or the color temperature in the mixed light.
Moreover, because of the trend of compact size of an LED package, the distance between LEDs and the wavelength conversion layer becomes smaller so that the non-uniform effect of the mixing light in the distribution of the color or the color temperature is more serious.